I have always had insurance on all my phones. You just never know and like it has been pointed out all ready the overall cost of the insurance plus the deductible is still less than the purchase price of the phone should you have to replace it.
As for the question regarding the screen protectors. I use them I also put them on my husbands phone. He carries his phone in his pocket and the screen protector seems to keep the change and keys from scratching the screen. But those are a total preference. Some will tell you no you do not need it because of the gorilla glass. So that one is up to you.